Mitsubishi Electric MELSEC iQ-R Series User Manual page 130

A load inputs data incorrectly due to a chattering.
Cause A device with a high input response speed is connected to the contact output module.
Action Use a transistor output module.
At output On, even loads in connection to other output simultaneously turn on.
The following fault example and its corrective action are for the transistor output (source type).
Cause A non-connection state between the external power supply 0V and the common line of the load due to interruption or disconnection causes
a current to flow to the load in off state through the parasitic circuit connected to the output element in off state.
ON
OFF
Continuous use in this condition may cause a failure.
Action Correctly connect the external power supply and the load.
To prevent further occurrence of the situation above, insert diodes to each output terminal as shown below:
9 TROUBLESHOOTING
128
9.3 Output Circuit Troubles and Corrective Actions
Output
element
Output
control
Y0
circuit
Output
element
Output
control
Y1
circuit
COM
0V
Y0
Load
Y1
Load
COM
24V
0V
Load
Load
Switch off
or
disconnection
24V